Compound Machining Method and Apparatus

ABSTRACT

A milling tool and a workpiece each may be rotated at a rotational velocity of at least 25 m/min in a compound machining operation. Disclosed are a computer numerically controlled machine, a method for operation of a computer numerically controlled machine, a computer program product, and a method for determining compound machining parameters. In some embodiments, a processing parameter for compound machining is selected and other processing parameters are algorithmically determined based thereon.

RELATED APPLICATION

The present application claims the benefit of prior U.S. ProvisionalApplication 60/832,995 filed Jul. 25, 2006. The contents of thisprovisional application are hereby incorporated by reference in theirentirety.

TECHNICAL FIELD

The invention is in the field of machine tools, in particular computernumerically controlled machine tools.

BACKGROUND OF THE INVENTION

Machining processes such as milling, turning, broaching, shaping, andhobbing are processes that require relative motion between the work andthe tool. In conventional linear processes (shaping and broaching) thecutting speed, i.e., the velocity of relative motion between work andtool is equal to the feed velocity. In conventional rotating processes(turning, hobbing, and milling) the rotation of the work or tool allowscutting speeds that are greater than the feed velocity by typically twoorders of magnitude or more.

Traditionally, each of the cutting processes has been performed by amachine designed and built specifically for that process. For example, atypical turning machine, or lathe, rotates the workpiece at highvelocity against a tool moving on a linear path at a low velocity. Aconventional mill rotates a tool at high velocity against a workpiecemoving on a linear path at low velocity.

More recently, computer numerically controlled mill/turn machines havebecome available. Milling on these machines has been accomplished bysubstituting rotation of the work at very low velocities for linear feedat low velocity. The rotational speed of the work emulates the feedvelocity of conventional milling, typically one to ten feet per minute.The rotational velocity of a milling tool typically falls between 100and 10,000 feet per minute, with most operations performed between 500and 2,000 feet per min.

SUMMARY

It has been found that a machine may be operated in a compound machiningoperation, wherein both the workpiece and the tool move (in many caseseach by rotating) when the tool is in contact with the workpiece. Forinstance, a rotating workpiece and a rotating tool may be provided, andthe tool and workpiece each may be rotating when brought into contactwith one another. In some embodiments this allows an increase in powerthat is applied to the workpiece relative to, for instance, aconventional turning operation.

The rotation of the tool and of the workpiece together result in arelative velocity of rotation between the tool and workpiece. The samerelative velocity may be obtained under various different processingparameters, including rotational speed of the tool, rotational speed ofthe workpiece, and feed rate. In some embodiments, the inventioncontemplates algorithmic determination of processing parameters toenable a compound machining operation given one or more selectedparameters. For instance, a relative velocity and workpiece rotationalspeed may be selected, and other processing parameters, such as a feedrate and tool rotational velocity, may be determined therefrom. In someembodiments, the algorithmic computations may be performed on a machine,such as a computer numerically controlled machine. In other embodiments,the algorithmic computations may be performed manually or on a computingdevice remote from the machine.

In some embodiments, the invention provides a computer program productcomprising a computer-readable medium having disposed thereon code forcausing calculations and/or machine operations in accordance with thesubject matter described herein. The computer-readable medium may be acomponent of a computer numerically controlled machine (such as a memoryor storage device thereof) or may be a computer readable medium that isnot a component thereof (for instance, a memory or storage of a separatecomputing device).

In some embodiments, a computer numerically controlled machine isprovided. The computer numerically controlled machine may contain acomputer program product having disposed thereon code for causingcalculations and/or code for causing machine operations in accordancewith the subject matter described herein.

In some embodiments, a machine having at least a first retainer and asecond retainer is provided. The first retainer retains a workpiece andthe second retainer retains a rotating tool. In any suitable order, theworkpiece and tool each are rotated at a surface velocity of at least 25m/min. The first retainer is moved relative to the second retainer in adirection having at least a z-axis component to cause the tool tocontact the workpiece. The rotation of the tool relative to theworkpiece is sufficient to result in removal of material from theworkpiece, and in some embodiments, to result in removal of discretechips of material from the workpiece. The rotation of the tool andworkpiece may be synchronous or asynchronous, or asynchronous over aportion of the range of travel of the tool relative to the workpiece asis sufficient to remove a discrete chip of material from the workpiece.The machine may be a computer numerically controlled machine.

In another embodiment, the invention provides a computer numericallycontrolled machine that is provided with a computer readable medium thatcontains programming to accomplish the foregoing.

In certain embodiments, the invention provides a number of advantages.By causing rotation of the workpiece and the tool, an increase inoverall processing power may be provided in some embodiments relative toconventional roughing operations without causing a significant increasein torque on the workpiece or main spindle. In some embodiments, theduty cycle of the tool is reduced, such that the tool may be rotated ata higher rotational speed than is conventionally permitted withoutincurring disabling thermal damage to the tool. The machine may beoperated in some embodiments to remove discrete broken chips from theworkpiece rather than a single unbroken chip, thus reducing machinedowntime and facilitating processing.

Milling and other tooling operations generally may be accomplished inmultiple steps, typically including one or more roughing operations inwhich relatively large amounts of material are removed from theworkpiece, and typically also including one or more finishing operationin which relatively small amounts of material are removed from theworkpiece. The invention, in certain embodiments, contemplates roughingoperations performed in a computer numerically controlled machine. Insome embodiments, such as knurling or grooving operations, the surfaceyielded after a compound machining operation may itself be regarded asthe finished surface. In practice, operation of a computer numericallycontrolled machine in accordance with certain embodiments of theinvention has resulted in a workpiece with a knurled-like pattern on thesurface. The invention contemplates an apparatus and method for forminga knurled surface on a workpiece. Additionally, the inventioncontemplates embodiments in which processing parameters effective toproduce a desired knurled-like pattern are selected, and in whichcomputer numerically controlled machine is operated in accordance withthe selected parameters to remove material from a workpiece to form aknurled-like pattern on the surface of the workpiece.

DESCRIPTION OF THE FIGURES

FIG. 1 is a front elevation of a computer numerically controlled machinein accordance with one embodiment of the present invention, shown withsafety doors closed;

FIG. 2 is a front elevation of a computer numerically controlled machineillustrated in FIG. 1, shown with the safety doors open;

FIG. 3 is a perspective view of certain interior components of thecomputer numerically controlled machine illustrated in FIGS. 1 and 2,depicting a machining spindle, a first chuck, a second chuck, and aturret;

FIG. 4 a perspective view, enlarged with respect to FIG. 3 illustratingthe machining spindle and the horizontally and vertically disposed railsvia which the spindle may be translated;

FIG. 5 is a side view of the first chuck, machining spindle, and turretof the machining center illustrated in FIG. 1;

FIG. 6 is a view similar to FIG. 5 but in which a machining spindle hasbeen translated in the Y-axis;

FIG. 7 is a front view of the spindle, first chuck, and second chuck ofthe computer numerically controlled machine illustrated in FIG. 1,including a line depicting the permitted path of rotational movement ofthis spindle;

FIG. 8 is a perspective view of the second chuck illustrated in FIG. 3enlarged with respect to FIG. 3;

FIG. 9 is a perspective view of the first chuck and turret illustratedin FIG. 2, depicting movement of the turret and turret stock in theZ-axis relative to the position of the turret in FIG. 2;

FIG. 10 is a representation of a portion of a computer numericallycontrolled machine operating in accordance with a prior art millingprocess;

FIG. 11 is a representation of a portion of a computer numericallycontrolled machine operating in accordance with one embodiment of theinvention, illustrating a compound machining operation;

FIG. 12 is a front view, and 13 a perspective view, of a tool andworkpiece in a compound machining operation in accordance with oneembodiment of the invention, the workpiece being retained within a chuckof a computer numerically controlled machine and a honing tool beingretained in a spindle of the machine;

FIG. 14 is a front view, and FIG. 15A a perspective view, of a tool andworkpiece in a compound machining operation performed in accordance withanother embodiment of the invention, the workpiece being retained withina chuck of a computer numerically controlled machine and a peripheralcutting and end mill being retained within a spindle of the machine,FIG. 14 illustrating the beginning of the operation and FIG. 15Aillustrating the operation in progress;

FIGS. 15B-D are perspective views of tools and workpieces alternativecompound machining operations;

FIG. 16 is a representational view of a tool and workpiece in a compoundmachining operation in accordance with another embodiment of theinvention, illustrating use of a turning tool in combination with amilling tool;

FIG. 17 is a perspective view of a workpiece that has been roughened inaccordance with one embodiment of the invention, illustrating a surfacehaving a knurled-like pattern.

The figures are not intended to be scale. For instances, in FIGS. 10 and11, the difference between the initial and machined diameter of theworkpieces illustrated is exaggerated for purposes of discussion.

DETAILED DESCRIPTION

The invention provides, in one embodiment, a method comprising, for aworkpiece and a milling tool, selecting at least one processingparameter for a compound machining operation in which the workpiece andmilling tool each rotate at a rate of at least 25 m/min, andalgorithmically determining other processing parameters for saidcompound machining operation.

The invention provides, in another embodiment, a computer programproduct comprising a computer readable medium having disposed thereoncode for algorithmically determining processing parameters for acompound machining operation for a workpiece and a milling tool given atleast one a selected processing parameter for a compound machiningoperation.

The invention provides, in another embodiment, a computer numericallycontrolled machine comprising at least first and second retainers, eachof said first and second retainers comprising one of a spindle retainer,a turret retainer, a first chuck and a second chuck; at least onecutting tool, said at least one cutting tool being operatively connectedto said one of said retainers; and a computer control system operativelycoupled to said first retainer and to said second retainer and causingsaid first retainer to move relative to said second retainer, saidcomputer control system including a computer readable medium havingdisposed thereon code for algorithmically determining processingparameters effective for compound machining of a workpiece using a tool,given a preselected processing parameter for said compound machining.

The invention provides, in another embodiment, a method comprisingproviding a computer numerically controlled machine, said machine havingat least a first retainer retaining a workpiece, and a second retainerretaining a milling tool, and in any suitable order, rotating saidworkpiece and rotating said tool, each of said workpiece and said toolbeing rotated to provide a surface velocity of at least 25 m/min, andmoving said first retainer relative to said second retainer to causesaid tool to contact said workpiece in a compound machining operation.

The invention provides, in another embodiment, a computer numericallycontrolled machine comprising at least first and second retainers, eachof said first and second retainers comprising one of a spindle retainer,a turret retainer, a first chuck and a second chuck, at least onecutting tool, said at least one cutting tool being operatively connectedto said one of said retainers; and a computer control system operativelycoupled to said first retainer and to said second retainer and causingsaid first retainer to move relative to said second retainer, saidcomputer control system including a computer readable medium havingdisposed thereon code for causing in any suitable order rotation of saidworkpiece and rotation said tool to provide a surface velocity of atleast 25 m/min for each of said workpiece and said tool; and for causingsaid first retainer to move relative to said second retainer to causesaid tool to contact said workpiece in a compound milling operation.

The invention provides, in another embodiment, a method comprisingproviding a computer numerically controlled machine, said machine havingat least a first retainer retaining a workpiece, and a second retainerretaining a tool, and in any suitable order, rotating said workpiece androtating said tool, each of said workpiece and said tool being rotatedto provide a surface velocity of at least 25 m/min; and moving saidfirst retainer relative to said second retainer to cause said tool tocontact said workpiece and to remove material to thereby cause formationof a knurled-like pattern on the surface of said workpiece.

The invention provides, in another embodiment, a method comprisingproviding a computer numerically controlled machine, said machine havingat least a first retainer retaining a workpiece, and a second retainerretaining a tool, selecting processing parameters effective forformation of a knurled-like pattern on the surface of said workpiece,said processing parameters comprising speed of rotation of a workpiece,speed of rotation of a tool, and a phase difference between saidrotation of said workpiece and said rotation of said tool, the rotationof said tool relative to said workpiece being sufficiently asynchronousto cause formation of a knurled surface on said workpiece; and operatingsaid computer numerically controlled machine under said processingparameters to remove material to provide a knurled-like pattern on atleast a portion of said workpiece.

The invention provides, in another embodiment, a computer numericallycontrolled machine comprising at least first and second retainers, eachof said first and second retainers comprising one of a spindle retainer,a turret retainer, a first chuck and a second chuck, at least onecutting tool, said at least one cutting tool being operatively connectedto said one of said retainers, and a computer control system operativelycoupled to said first retainer and to said second retainer and causingsaid first retainer to move relative to said second retainer, saidcomputer control system including a computer readable medium havingdisposed thereon code for causing rotation of a workpiece at arotational velocity of at least 25 m/min and code for causing rotationof a tool at a rotational velocity of at least 25 m/min, and code forcausing said first retainer to move relative to said second retainer tocause said tool to contact said workpiece under processing conditionseffective to cause discrete chips of material to be removed from saidworkpiece.

The invention provides, in another embodiment, a method for determiningthe suitability of compound machining parameters, comprisingdetermining, for a workpiece of a preselected size and material, and atool of a preselected configuration, a relative velocity of rotationbetween said tool and said workpiece; and determining whether the poweravailability of a computer numerically controlled machine is sufficientto permit compound machining at said relative contact rate.

The invention provides, in another embodiment, a computer programproduct comprising a computer readable medium containing computerprogram code for determining, for a workpiece of a preselected size andmaterial, and a tool of a preselected configuration, a relative velocityof rotation between said tool and said workpiece; and for determiningwhether the power availability of a computer numerically controlledmachine is sufficient to permit compound machining at said relativecontact rate.

The foregoing embodiments are not mutually exclusive.

The invention contemplates, in some embodiments, various compoundmachining operations that may be performed using a computer numericallycontrolled machine. The invention is not limited to a specific type ofcompound machining operation, and it is contemplated that operationssuch as knurling, grooving, roughing, and the like may be performed inconnection with the present teachings. In some embodiments the inventioncontemplates algorithmic determination of processing parameters for acompound machining operation; in other embodiments, the inventioncontemplates a computer numerically controlled machine, and in otherembodiments, the invention contemplates a computer program comprising acomputer-readable medium having program code disposed thereon. Again, inthese embodiments, the invention is not limited to a specific type ofcompound machining operation.

Except as otherwise claimed, the invention is not limited to embodimentswherein both the tool and workpiece rotate. It is contemplated, forinstance, that the compound machining operation may employ a workpiecethat translates rapidly relative to a tool. In many embodiments,however, the tool and workpiece each rotate. Similarly, unless otherwiseclaimed, the invention is not limited to operation on a computernumerically controlled machine, and it is contemplated that machinesthat are otherwise controlled are operable.

By rotating both the workpiece and the tool in a compound machiningoperation, material may be removed from the workpiece. Generally,numerous variables can affect the compound machining operation. Thesecan include, for instance and without limitation, the workpiece diameter(D_(W)), the rotational speed of the tool (N_(T)) (expressed as 1/time,for instance as RPM), the rotational speed of the workpiece (N_(W)), thewidth of the tool (W_(T)), the tool diameter (D_(T)), the number ofcutting teeth on the tool (Z_(T)), the feed rate (FR) (sometimesexpressed as a feed rate per tooth (F_(T))), the desired turningvelocities of the workpiece and tool (V_(W) and V_(T), each representingthe velocity of a point on the surface of the workpiece or tool), thedepth of cut (DOC_(T)) the composition of the workpiece, the angle ofimpingement of the tool on the workpiece, and other factors.Additionally, the ability to effectuate compound machining is limited bythe power available in the computer numerically controlled machine.

The relative velocity of rotation (V_(R)) between a tool and workpiececan be related according to the following algorithm:V _(R) =DIR1*(V _(W))+DIR2*(V _(T))

where DIR1 and DIR2 are variables that account for the angle at whichthe tool contacts the workpiece and/or for the direction of rotation ofthe tool and workpiece. V_(R) is a velocity figure, expressibleconveniently in units such as surface feet per minute (SFM). Problemsmay arise in the machining process if the relative velocity (V_(R))between the tool and the workpiece approaches zero. Certaincharacteristics of the tool and the machining process can affect howclosely V_(R) can approach to zero, such as the clearance angle of thecutting edge and the radius of the tool.

In accordance with one embodiment of the invention, one or moreprocessing parameters for compound machining are selected, and one ormore other processing parameters are algorithmically determined. Forinstance, in accordance with one embodiment, a V_(R) is selected to beapproximately equal to a predetermined or preselected desired millingvelocity, and one or more other parameters of the compound machiningoperation are determined based thereon. In some embodiments, both V_(R)and another parameter are selected, and other processing parameters areselected based thereon. For instance, in some embodiments, both V_(R)and V_(W) are selected, and other processing parameters are determinedbased thereon. In some embodiments, both V_(R) and N_(W) are selected,and other processing parameters are determined based thereon.

The limits of the computer numerically controlled machine and toolemployed, and possibly other limits and restrictions, may affect theselection of processing parameters. For instance, if a selected V_(R)and V_(W) would require a tool rotational speed that is beyond themaximum tool rotational speed of the computer numerically controlledmachine, new processing parameters should be selected. Similarly, if theprocessing power required would exceed the power of the computernumerically controlled machine, new parameters should be selected.

In some embodiments, the rotation of the tool and workpiece may besynchronous within the limits of operation of the machine. In otherembodiments, the rotation of the tool and workpiece are asynchronousover the entire range of travel of the tool relative to the workpiece.Asynchronous rotation contemplates rotation with a difference inrelative phase between the tool and workpiece, such that the radialposition of the tool and workpiece upon initial contact do not coincideat the same rotational position over a suitable given period. Therotation of the tool relative to the workpiece may be completelyasynchronous over the entire course of a compound machining operation.In some embodiments, the rotation of the tool relative to the workpieceis asynchronous over a portion of the range of travel of the toolrelative to the workpiece as is sufficient to remove a discrete chip ofmaterial from the workpiece. For instance, the rotation of the tool andworkpiece may be sufficiently asynchronous to cause discrete chips ofmaterial to be removed from the workpiece. The rotational ratio of thetool rotation to workpiece rotation will depend on factors including,inter alia, the feed rate. Generally, an asynchronous tool rpm:workpiecerpm ratio is not a lower integer multiple (1:1, 2:1, 3:1, etc.) but maybe a ratio such as 1.0001:1 or any other suitable value.

For instance, one method for determining suitable compound machiningparameters can proceed per the following (these steps need not beperformed in the order recited):

(1) After selecting V_(W), calculate a workpiece RPM:$\underset{({rpm})}{Nw} = \frac{12 \times V_{w}}{D_{w} \times \pi}$

In this equation, V_(W) is provided in surface feet per minute (SFM),and D_(W) in inches. A similar calculation may be made for metric orother units.

(2) Confirm that the workpiece RPM does not exceed the capacity of thecomputer numerically controlled machine (e.g. the lathe main spindle).

(3) Calculate the desired tool velocity:$\underset{({SFM})}{V_{T}} = \frac{{D_{T} \times \pi}*N_{T}}{12}$

(4) Adjust the tool or workpiece velocities, or the tool:workpiecerotational ratio (R_(W)), depending on the desired surfacecharacteristics. For instance, tool and workpiece may be rotatedasynchronously over some or all of the range of travel of the toolrelative to the workpiece, or may be rotated synchronously within thelimits of operation of the machine.

(5) Calculate a feed rate:FR=F _(T) *N _(W) *Z _(T)

The power requirements of the compound machining operation may beevaluated as against the power available in the computer numericallycontrolled machine:

(6) Calculate material removal rates for milling and turning aspects:MRR(milling)=W _(T) *F _(T) *V _(W)*12MRR(turning)=12*V _(W) *F _(T) *DOC _(T)

(7) Calculate the power required for milling and turning aspects:Power(milling)=MRR(milling)*material K factorPower(turning)=MRR(turning)*material K factor

(8) Calculate the total power available for turning:${{Torque}\quad{transferred}} = \frac{{{Power}({milling})}*D_{W}}{2*V_{T}}$${{Additional}\quad{Turning}\quad{Power}} = \frac{{Torque}\quad{transferred}*V_{W}}{R_{W}}$ Total power available=Power(main spindle)+Additional Turning Power

(9) Confirm that the total power available for milling does not exceedthe power of the tool spindle.

(10) Confirm that the power required for turning does not exceed thetotal power available for turning.

In some embodiments, the power of the tool and main spindles may bedetermined with reference to spindle power curves.

The foregoing has been described with reference to selection of thedesired feed rate and workpiece turning velocity, but other parametersmay be selected. For instance, in some embodiments, the desired feedrate and tool turning velocity may be selected, and the workpieceturning velocity and feed rate may be algorithmically determined. Inother embodiments, other parameters are selected. In some embodiments,at least two parameters are selected. For instance, in some embodiments,two parameters are selected, one being a relative velocity of rotationand another being one of a tool rotational parameter (rotational rate orrotational velocity) and a workpiece rotational parameter (rotationalrate or rotational velocity) are selected, and other processingparameters including at least a feed rate are determinedalgorithmically. The algorithmic determinations are not limited to theforegoing equations, and it is contemplated that other algorithmicdeterminations may be made.

Any suitable apparatus may be employed in conjunction with the methodsof invention. In some embodiments, the methods are performed using acomputer numerically controlled machine, illustrated generally in FIGS.1-9. A computer numerically controlled machine is itself provided inother embodiments of the invention. The machine 100 illustrated in FIGS.1-9 is an NT-series machine, versions of which are available from MoriSeki USA, Inc., the assignee of the present application. Other suitablecomputer numerically controlled machines include the NL-series machineswith turret, also available from Mori Seiki USA, Inc. (not shown). Othermachines may be used in conjunction with the invention.

In general, with reference to the NT-series machine illustrated in FIGS.1-3, one suitable computer numerically controlled machine 100 has atleast a first retainer and a second retainer, each of which may be oneof a spindle retainer associated with spindle 144, a turret retainerassociated with a turret 108, or a chuck 110, 112. In the embodimentillustrated in the Figures, the computer numerically controlled machine100 is provided with a spindle 144, a turret 108, a first chuck 110, anda second chuck 112. The computer numerically controlled machine 100 alsohas a computer control system 114 operatively coupled to the firstretainer and to the second retainer for controlling the retainers, asdescribed in more detail below. It is understood that in someembodiments, the computer numerically controlled machine 100 may notcontain all of the above components, and in other embodiments, thecomputer numerically controlled machine 100 may contain additionalcomponents beyond those designated herein.

As shown in FIGS. 1 and 2, the computer numerically controlled machine100 has a machine chamber 116 in which various operations generally takeplace upon a workpiece (not shown). Each of the spindle 144, the turret108, the first chuck 110, and the second chuck 112 may be completely orpartially located within the machine chamber 116. In the embodimentshown, two moveable safety doors 118 separate the user from the chamber116 to prevent injury to the user or interference in the operation ofthe computer numerically controlled machine 100. The safety doors 118can be opened to permit access to the chamber 116 as illustrated in FIG.2. The computer numerically controlled machine 100 is described hereinwith respect to three orthogonally oriented linear axes (X, Y, and Z),depicted in FIG. 4 and described in greater detail below. Rotationalaxes about the X, Y and Z axes are connoted “A,” “B,” and “C” rotationalaxes respectively.

The computer numerically controlled machine 100 is provided with acomputer control system for controlling the various instrumentalitieswithin the computer numerically controlled machine. In the illustratedembodiment, the machine is provided with two interlinked computersystems, a first computer system comprising a user interface system(shown generally at 114 in FIG. 1) and a second computer system (notillustrated) operatively connected to the first computer system. Thesecond computer system directly controls the operations of the spindle,the turret, and the other instrumentalities of the machine, while theuser interface system 114 allows an operator to control the secondcomputer system. Collectively, the machine control system and the userinterface system, together with the various mechanisms for control ofoperations in the machine, may be considered a single computer controlsystem. In some embodiments, the user operates the user interface systemto impart programming to the machine; in other embodiments, programs canbe loaded or transferred into the machine via external sources. It iscontemplated, for instance, that programs may be loaded via a PCMCIAinterface, an RS-232 interface, a universal serial bus interface (USB),or a network interface, in particular a TCP/IP network interface. Inother embodiments, a machine may be controlled via conventional PLC(programmable logic controller) mechanisms (not illustrated).

As further illustrated in FIGS. 1 and 2, the computer numericallycomputer controlled machine 100 may have a tool magazine 142 and a toolchanging device 143 (shown in FIGS. 1 and 2). These cooperate with thespindle 144 to permit the spindle to operate with a variety of cuttingtools (shown in FIG. 1 as tools 102′). The spindle 144 is mounted on acarriage assembly 120 that allows for translational movement along theX- and Z-axes, and on a ram 132 that allows the spindle 144 to be movedin the Y-axis. The ram 132 is equipped with a motor to allow rotation ofthe spindle in the B-axis, as set forth in more detail hereinbelow. Asillustrated, the carriage assembly has a first carriage 124 that ridesalong two threaded vertical rails (one rail shown at 126) to cause thefirst carriage 124 and spindle 144 to translate in the X-axis. Thecarriage assembly also includes a second carriage 128 that rides alongtwo horizontally disposed threaded rails (one shown in FIG. 3 at 130) toallow movement of the second carriage 128 and spindle 144 in the Z-axis.Each carriage 124, 128 engages the rails via plural ball screw deviceswhereby rotation of the rails 126, 130 causes translation of thecarriage in the X- or Z-direction respectively. The rails are equippedwith motors 170 and 172 for the horizontally disposed and verticallydisposed rails respectively.

The spindle 144 holds the cutting tool 102 by way of a spindleconnection and a tool holder 106. The spindle connection 145 (shown inFIG. 2) is connected to the spindle 144 and is contained within thespindle 144. The tool holder 106 is connected to the spindle connectionand holds the cutting tool 102. Various types of spindle connections areknown in the art and can be used with the computer numericallycontrolled machine 100. Typically, the spindle connection is containedwithin the spindle 144 for the life of the spindle. An access plate 122for the spindle 144 is shown in FIGS. 5 and 6.

The first chuck 110 is provided with jaws 136 and is disposed in a stock150 that is stationary with respect to the base 111 of the computernumerically controlled machine 110. The second chuck 112 is alsoprovided with jaws 137, but the second chuck 112 is movable with respectto the base 111 of the computer numerically controlled machine 100. Morespecifically, the machine 100 is provided with threaded rails 138 andmotors 139 for causing translation in the Z-direction of the secondstock 152 via a ball screw mechanism as heretofore described. To assistin swarf removal, the stock 152 is provided with a sloped distal surface174 and a side frame 176 with Z-sloped surfaces 177, 178. Hydrauliccontrols and associated indicators for the chucks 110, 112 may beprovided, such as the pressure gauges 182 and control knobs 184 shown inFIGS. 1 and 2. Each stock is provided with a motor (161, 162respectively) for causing rotation of the chuck.

The turret 108, which is best depicted in FIGS. 5, 6 and 9, is mountedin a turret stock 146 that also engages rails 138 and that may betranslated in a Z-direction, again via ball-screw devices. The turret108 is provided with various turret connectors 134, as illustrated inFIG. 9. Each turret connector 134 can be connected to a tool holder 135or other connection for connecting to a cutting tool 102. Since theturret 108 can have a variety of turret connectors 134 and tool holders135, a variety of different cutting tools 102 can be held and operatedby the turret 108. The turret 108 may be rotated in a C′ axis to presentdifferent ones of the tool holders (and hence, in many embodiments,different tools) to a workpiece.

It is thus seen that a wide range of versatile operations may beperformed. With reference to tool 102 held in tool holder 106, such tool102 may be brought to bear against a workpiece (not shown) held by oneor both of chucks 110, 112. When it is necessary or desirable to changethe tool 102, a replacement tool 102 may be retrieved from the toolmagazine 142 by means of the tool changing device 143. With reference toFIGS. 4 and 5, the spindle 144 may be translated in the X and Zdirections (shown in FIG. 4) and Y direction (shown in FIGS. 5 and 6).Rotation in the B axis is depicted in FIG. 7, the illustrated embodimentpermitting rotation within a range of 120° to either side of thevertical. Movement in the Y direction and rotation in the B axis arepowered by motors (not shown) that are located behind the carriage 124.Generally, as seen in FIGS. 2 and 7, the machine is provided with aplurality of vertically disposed leaves 180 and horizontal disposedleaves 181 to define a wall of the chamber 116 and to prevent swarf fromexiting this chamber.

The components of the machine 100 are not limited to the heretoforedescribed components. For instance, in some instances an additionalturret may be provided. In other instances, additional chucks and/orspindles may be provided. Generally, the machine is provided with one ormore mechanisms for introducing a cooling liquid into the chamber 116.

In the illustrated embodiment, the computer numerically controlledmachine 100 is provided with numerous retainers. Chuck 110 incombination with jaws 136 forms a retainer, as does chuck 112 incombination with jaws 137. In many instances these retainers will alsobe used to hold a workpiece. For instance, the chucks and associatedstocks will function in a lathe-like manner as the headstock andoptional tailstock for a rotating workpiece. Spindle 144 and spindleconnection 145 form another retainer. Similarly, the turret 108, whenequipped with plural turret connections 134, provides a plurality ofretainers (shown in FIG. 9).

The computer numerically controlled machine 100 may use any of a numberof different types of cutting tools known in the art or otherwise foundto be suitable. For instance, the cutting tool 102 may be a millingtool, a drilling tool, a grinding tool, a blade tool, a broaching tool,a turning tool, or any other type of cutting tool deemed appropriate inconnection with a computer numerically controlled machine 100. Asdiscussed above, the computer numerically controlled machine 100 may beprovided with more than one type of cutting tool, and via the mechanismsof the tool changing device 143 and magazine 142, the spindle 144 may becaused to exchange one tool for another. Similarly, the turret 108 maybe provided with one or more cutting tools 102, and the operator mayswitch between cutting tools 102 by causing rotation of the turret 108to bring a new turret connection 134 into the appropriate position.

Other features of a computer numerically controlled machine include, forinstance, an air blower for clearance and removal of chips, variouscameras, tool calibrating devices, probes, probe receivers, and lightingfeatures. The computer numerically controlled machine illustrated inFIGS. 1-9 is not the only machine of the invention, but to the contrary,other embodiments are envisioned.

In prior art operations, as shown in FIG. 10, tool 201 rotates indirection 202 and workpiece 203 rotates in direction 204. The workpiece203 has initial diameter 205 and machined diameter 206 which resultsupon removal of material from the workpiece. The tool contains tool tipsor teeth 207, which contact the workpiece to cause removal of materialtherefrom. The workpiece turns in direction represented by arrow at aspeed that is typically very low, on the order sufficient to provide asurface velocity typically of less than 10 m/min. Arrow 204alternatively may represent motion of the tool around a stationaryworkpiece.

In accordance with one embodiment, a machine as described hereinabove,or another suitable machine, is provided. The machine has a firstretainer that retains a workpiece and a second retainer that retains atool. It is contemplated that the tool employed in a compound machiningoperation may be a milling tool, that is, a tool with a defined cuttingsurface (unlike a grinding tool). Numerous milling tools are known inthe art, and it is contemplated that known milling tools or other toolsas may be found to be suitable may be employed in conjunction with theinvention.

As illustrated, for instance, in FIGS. 12 and 13, the tool 208 may beretained in a spindle 144 (not shown in FIG. 12) and a workpiece 209 maybe retained in the chuck 110 of the machine. Alternatively, the tool maybe retained in another retainer in the machine such as a turretretainer. The tool and the workpiece each are rotated, in someembodiments to provide a surface velocity of at least 25 m/min. Thefirst retainer is moved relative to the second retainer in a directionhaving at least a z-axis component (e.g. direction 225, as illustratedin FIGS. 14 and 16) to cause the tool to contact the workpiece. Eitherthe tool or the chuck, or both, may be moved relative to the machine.Preferably, the infeed per revolution of the work is kept small enoughto minimize the change in clearance geometry of the cutting edge betweenthe time the tool engages the work and when it exits.

In the embodiment shown in FIG. 11, tool 210 rotates in direction 211,and workpiece 212 rotates in direction 213. The tool contains tool tipsor teeth 207A, which contact the workpiece to cause removal of materialtherefrom. In the illustrated embodiment, the tool rotates about an axisof rotation that is parallel to the axis of rotation of the workpiece.Both the tool and the workpiece may be rotated sufficiently to provide asurface velocity of 25 m/min or more. For instances, the surfacevelocity may be at least 50 m/min, at least 75 m/min, at least 100m/min, at least 150 m/min at least 200 m/min, at least 250 m/min, atleast 300 m/min, at least 400 m/min, at least 500 m/min, at least 1,000m/min, at least 2,000 m/min, at least 5,000 m/min, at least 6,000 m/min,or any other suitable value.

FIG. 11 illustrates rotation of the tool in an axis that is parallel tothe axis of rotation of the workpiece, but other orientations arepossible. For instance, as shown in FIGS. 15C and 15D, the tool may berotated in an axis that is perpendicular to a plane that contains theaxis of rotation of the workpiece and that contains to the point ofcontact of the tool and workpiece. In these embodiments, generally ahelical tool may be employed. The V_(R) will be calculated with adirectional factor DIR that accounts for the angle of the helix.

In other embodiments, the tool rotates in an axis that is oblique to aplane that contains the axis of rotation of the workpiece and the pointof contact of the tool 220 and workpiece 222, as illustrated, forinstance, in FIGS. 15A and B.

The tool may be rotated in a positive direction or in a negativedirection relative to the rotating workpiece. In the negative directionof rotation, a point of contact on the tool surface and a point ofcontact on the workpiece surface move in tangential directions that arethe same relative to each other. In other words, in the positivedirection of rotation, the tool and the workpiece are rotating at leastpartially “with” each other. Rotation of the tool in the negativedirection is illustrated in FIG. 15A via arrows 211, 213. In thepositive direction of rotation, a point of contact on the tool surfaceand a point of contact on the workpiece surface move in tangentialdirections that are opposite relative to each other. In other words, inthe positive direction of rotation, the tool and the workpiece arerotating at least partially “against” each other. Rotation of the toolin a positive direction is illustrated in FIG. 15B via arrows 214, 215.When milling tools are rotated in a negative direction, generallyspeaking tools with a high helix are generally desirable. A portion ofthe cutting forces will be applied axially, reducing the torque requiredof the milling spindle.

FIGS. 18-21 illustrate various configurations of a workpiece 230 and atool 232 having an insert 234 with a cutting edge 236. FIG. 18illustrates negative relative rotation between the tool and theworkpiece, and calculation of V_(R) is subtractive in nature. In thisconfiguration, machining will occur successfully when V_(W)>V_(T), whichensures that the cutting edge 236 of the tool insert 234 properlycontacts the workpiece. As described above, when V_(R) approaches zero(i.e., V_(W) approaches V_(T)), problems such as tool breakage mayoccur. FIG. 19 also illustrates negative relative rotation between thetool and the workpiece, and calculation of V_(R) is subtractive innature. In this configuration, machining will occur successfully whenV_(W)<V_(T), which ensures that the cutting edge 236 of the tool insert234 properly contacts the workpiece. As described above, when V_(R)approaches zero, problems such as tool breakage may occur. FIG. 20illustrates positive relative rotation between the tool and theworkpiece, and calculation of V_(R) is additive in nature. In thisconfiguration, machining will occur successfully at all times, becausethe cutting edge 236 of the tool insert 234 always properly contacts theworkpiece. FIG. 21 illustrates positive relative rotation between thetool and the workpiece. In this configuration, machining will not occursuccessfully, because the cutting edge 236 of the tool insert 234improperly contacts the workpiece.

As illustrated in FIGS. 12, 13, 14, and 16, various tools may be broughtto bear on the surface of the workpiece. FIG. 14 illustrates a tool 224and a workpiece 226, and FIG. 16 illustrates two tools 227, 228, and aworkpiece 229. Other tools besides those shown may be employed, and theinvention is not contemplated to be limited to a particular type oftool. Generally, coated or uncoated tools may be employed, and each edgeof the tool can be manufactured from a wide variety of materialsdepending on sensitivity to cost and the material to be machined. Forinstance, carbides are typically used for the tools when cutting steels,while ceramics are commonly used to machine irons and high temperaturealloys. CBN is typically used for hardened steels and irons. Diamond(natural or synthetic) is used to machine aluminum, titanium, certainplastics, and the like. The cutting tools can be coated to improve theirlife. Where the mode of failure is abrasive, the coating may be harderthan the substrate. Where the mode of failure is associated with heat,the coating may be refractory. The tools are sometimes provided withcooling means, typically based on oil or water, although liquid nitrogenand other materials are occasionally used. These illustrations andguidelines are exemplary, and, in practice, any suitable tool may beused. The tools may be provided with devices for delivering coolingfluids. Such fluids typically are based on oil or water, although liquidnitrogen and other materials are occasionally used.

In some embodiments, a turning or other cutting tool, such as tool 228illustrated in FIG. 16, is used simultaneously or sequentially with themilling tool 227 employed in the compound machining operation. Thetooling turn typically will produce a single unbroken chip, andembodiments wherein solely discrete plural broken chips are desired,such a cutting tool ordinarily should not be used. The turning orcutting tool may be any tool suitable for use in a turning operation,and, in the context of the present invention connotes moving tools suchas tools with spinning or rotating inserts, as taught in U.S. Pat. No.7,156,006, issued Jan. 2, 2007.

In still other embodiments, multiple tools are used in a compoundmachining operation. For instance, certain computer numericallycontrolled machines available from Mori Seiki USA, Inc. contain multipleturrets, and it is contemplated that a turning or milling tool may beemployed in each operating turret retainer and in the spindle retainer.It is contemplated that a tool may be employed in a chuck of a computernumerically controlled machine.

As illustrated in FIG. 17, the surface that results from the compoundmachining operation may be a surface having a knurled-like pattern. Thesurface having the knurled-like pattern 219 shown in FIG. 17 is not thesole surface configuration formed in accordance with the invention, butto the contrary is representative of innumerable surface variants. Inmany cases, a subsequent finishing operation will be employed to furthermachine the surface having the knurled-like pattern to form a smoothsurface. Alternatively, in some embodiments, a knurled-like patternitself is desired. The invention contemplates selecting processingparameters effective for formation of a knurled-like pattern on theworkpiece, the processing parameters including the speed of rotation ofthe workpiece, speed of rotation of the tool, a feed rate and a phasedifference between the rotation of the workpiece and the rotation of thetool. Again, the rotation of the tool relative to the workpiece shouldbe sufficiently asynchronous to cause formation of the knurled-likepattern on the workpiece.

The invention contemplates not only methods for cutting a workpiece, butalso a computer numerically controlled machine. Generally, the computernumerically controlled machine includes at least first and secondretainers and at least one cutting tool. The first and second retainersgenerally should be selected from among a spindle retainer, a turretretainer, a first chuck, and a second chuck. A computer control system,such as the computer control system 114 described hereinabove, includesa computer readable medium having disposed thereon code for causingrotation of the workpiece at a determined speed and code for causingrotation of a tool at a determined speed with a phase difference betweenthe rotation of the workpiece and the rotation of the tool. The computerreadable medium also includes code for causing the first retainer tomove relative to the second retainer in a direction having at least az-axis component to cause the tool to contact the workpiece. Rotation ofthe tool relative to the workpiece again is sufficiently asynchronous tocause discrete chips in material to be removed from the workpiece. Acomputer numerically controlled machine that includes a computer systemthat controls the motion and feed rate of the workpiece and tool to formknurled-like pattern by material removal forms another embodiment of thepresent invention.

The following Tables provide certain parameters that have been foundsuitable in a Mori Seiki NT-series mill/turn center. Compound machiningoccurs at nonzero tool velocities. TABLE 1 SFM SFM SFM Diameter RPMDiameter RPM Feed Feed Example Tool Work Net Tool Tool Work Work per revVelocity — 0 1000 1000 1 0 4 955.414 0.01 9.55414 1 500 500 1000 11910.83 4 477.707 0.01 4.77707 2 −500 1500 1000 1 −1910.83 4 1433.120.01 14.3312 3 −1000 2000 1000 1 −3821.66 4 1910.83 0.01 19.1083 4 −20003000 1000 1 −7643.31 4 2866.24 0.01 28.6624 5 3000 −2000 1000 1 11465 4−1910.83 0.01 −19.1083 6 4000 −3000 1000 1 15286.6 4 −2866.24 0.01−28.6624 — 0 1000 1000 4 0 4 955.414 0.01 9.55414 7 500 500 1000 4477.707 4 477.707 0.01 4.77707 8 −500 1500 1000 4 −477.707 4 1433.120.01 14.3312 9 −1000 2000 1000 4 −955.414 4 1910.83 0.01 19.1083 10 −2000 3000 1000 4 −1910.83 4 2866.24 0.01 28.6624 11  3000 −2000 1000 42866.24 4 −1910.83 0.01 −19.1083 12  4000 −3000 1000 4 3821.66 4−2866.24 0.01 −28.6624

TABLE 2 SFM SFM SFM Diameter RPM Diameter RPM Feed Feed Example ToolWork Net Tool Tool Work Work per rev Velocity — 0 1000 1000 1 0 4955.414 0.01 9.55414 13 2000 1000 1000 1 7643.31 4 955.414 0.01 9.55414— 0 1000 1000 4 0 4 955.414 0.01 9.55414 14 2000 1000 1000 4 1910.83 4955.414 0.01 9.55414

In each of the foregoing examples the relative rotational velocitybetween the tool and workpiece was 1000 surface feet per minute, a valuetypical of cutting mild steel with carbide tools. By selecting differentvalues for the workpiece RPM, other parameters, including the tool RPMand the feed rate, were algorithmically determined in accordance withthe above teachings.

Thus, the invention in some embodiments recognizes a relative velocityof rotation between tool and workpiece and takes advantage of therelationship between relative velocity and tool and workpiece velocitiesto allow for algorithmic calculation of processing parameters. In someembodiments, the invention provides a method in which discrete chips ofmaterial are removed from a workpiece in a compound machining operation.In other embodiments it is seen that a computer numerically controlledmachine with specific computer programming is provided. In someembodiments, the inventive method allows conventional cutting tools tobe operated at two to ten times their normal speed. The machiningoperation can utilize two to ten times the usual power, but because theincrease in power is in direct proportion to the increase in speed, noincrease in peak torque is required, only an increase in the speed atwhich maximum torque in maintained. In some embodiments, the compoundmachining operation provides a duty cycle for the tool that permits thetool to be operated at a higher V_(T) than is conventionally possible.

The appended claims are incorporated by reference into the disclosure.All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference. In anylisting of possible ingredients or components, mixtures of the possibleingredients or components are contemplated unless expressly indicatedotherwise. The description or connotation, if any, of certainembodiments as “preferred” embodiments, and other recitation ofembodiments, features, or ranges as being preferred, is not deemed to belimiting, and the invention is deemed to encompass embodiments that arepresently deemed to be less preferred. All methods described herein canbe performed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended to illuminate the invention and does not pose a limitation onthe scope of the invention unless otherwise claimed. Any statementherein as to the nature or benefits of the invention or of the preferredembodiments is not intended to be limiting, and the appended claimsshould not be deemed to be limited by such statements. More generally,no language in the specification should be construed as indicating anynon-claimed element as being essential to the practice of the invention.This invention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.The description herein of any reference or patent or equipment, even ifidentified as “prior,” is not intended to constitute a concession thatsuch reference or patent is available as prior art against the presentinvention.

1. A method comprising: for a workpiece and a milling tool, selecting atleast one processing parameter for a compound machining operation inwhich the workpiece and milling tool each rotate at a rate of at least25 m/min, and algorithmically determining other processing parametersfor said compound machining operation.
 2. A method according to claim 1,including selecting at least two processing parameters for a compoundmachining operation.
 3. A method according to claim 2, comprisingselecting a desired relative velocity of rotation between said tool andsaid workpiece, and at least one other processing parameter selectedfrom a tool rotational parameter and a workpiece rotational parameter.4. A method according to claim 2, comprising selecting a desiredworkpiece rotational speed and a relative velocity of rotation betweensaid tool and said workpiece, said relative velocity approximating adesired milling velocity; and algorithmically determining otherprocessing parameters effective for compound machining of saidworkpiece.
 5. A method according to claim 1, comprising selecting adesired tool rotational speed and a relative velocity of rotationbetween said tool and said workpiece, said relative velocityapproximating a desired milling velocity; and algorithmicallydetermining other processing parameters effective for compound machiningof said workpiece.
 6. A method according to claim 1, said otherprocessing parameters comprising at least a tool rotational velocity anda feed rate.
 7. A method according to claim 1, comprising calculatingthe power required for compound machining and determining whetheravailable power permits compound machining at said selected processingparameter.
 8. A method according to claim 7, comprising selecting adifferent relative velocity if the available power does not permitcompound machining at said selected processing parameter.
 9. A methodaccording to claim 1, said other processing parameters being determinedremotely from a computer numerically controlled machine.
 10. A methodaccording to claim 1, said other processing parameters being determinedon a computer control system of a computer numerically controlledmachine.
 11. A method according to claim 1, including operating acomputer numerically controlled machine at a rotational velocity equalor approximately equal to said relative velocity and at said otherprocessing parameters.
 12. A computer program product comprising acomputer readable medium having disposed thereon code foralgorithmically determining processing parameters for a compoundmachining operation for a workpiece and a milling tool given at leastone a selected processing parameter for a compound machining operation.13. (canceled)
 14. (canceled)
 15. (canceled)
 16. A computer numericallycontrolled machine comprising at least first and second retainers, eachof said first and second retainers comprising one of a spindle retainer,a turret retainer, a first chuck and a second chuck; at least onecutting tool, said at least one cutting tool being operatively connectedto said one of said retainers; and a computer control system operativelycoupled to said first retainer and to said second retainer and causingsaid first retainer to move relative to said second retainer, saidcomputer control system including a computer readable medium havingdisposed thereon code for algorithmically determining processingparameters effective for compound machining of a workpiece using a toolgiven a preselected processing parameter for said compound machining.17. (canceled)
 18. A method comprising: providing a computer numericallycontrolled machine, said machine having at least a first retainerretaining a workpiece, and a second retainer retaining a milling tool;in any suitable order, rotating said workpiece and rotating said tool,each of said workpiece and said tool being rotated to provide a surfacevelocity of at least 25 m/min; and moving said first retainer relativeto said second retainer to cause said tool to contact said workpiece ina compound machining operation.
 19. (canceled)
 20. (canceled) 21.(canceled)
 22. (canceled)
 23. (canceled)
 24. (canceled)
 25. (canceled)26. (canceled)
 27. (canceled)
 28. (canceled)
 29. (canceled) 30.(canceled)
 31. (canceled)
 32. A computer numerically controlled machinecomprising; at least first and second retainers, each of said first andsecond retainers comprising one of a spindle retainer, a turretretainer, a first chuck and a second chuck; at least one cutting tool,said at least one cutting tool being operatively connected to said oneof said retainers; and a computer control system operatively coupled tosaid first retainer and to said second retainer and causing said firstretainer to move relative to said second retainer, said computer controlsystem including a computer readable medium having disposed thereon codefor causing in any suitable order rotation of said workpiece androtation said tool to provide a surface velocity of at least 25 m/minfor each of said workpiece and said tool; and for causing said firstretainer to move relative to said second retainer to cause said tool tocontact said workpiece in a compound milling operation.
 33. (canceled)34. (canceled)
 35. (canceled)
 36. (canceled)
 37. (canceled) 38.(canceled)
 39. (canceled)
 40. (canceled)
 41. (canceled)
 42. (canceled)43. A method comprising: providing a computer numerically controlledmachine, said machine having at least a first retainer retaining aworkpiece, and a second retainer retaining a tool; in any suitableorder, rotating said workpiece and rotating said tool, each of saidworkpiece and said tool being rotated to provide a surface velocity ofat least 25 m/min; and moving said first retainer relative to saidsecond retainer to cause said tool to contact said workpiece and tothereby cause formation of a knurled surface on said workpiece.
 44. Amethod comprising: providing a computer numerically controlled machine,said machine having at least a first retainer retaining a workpiece, anda second retainer retaining a tool; selecting processing parameterseffective for formation of a knurled surface on said workpiece, saidprocessing parameters comprising speed of rotation of a workpiece, speedof rotation of a tool, and a phase difference between said rotation ofsaid workpiece and said rotation of said tool, the rotation of said toolrelative to said workpiece being sufficiently asynchronous to causeformation of a knurled surface on said workpiece; and operating saidcomputer numerically controlled machine under said processing parametersto provide a knurled surface on at least a portion of said workpiece.45. A computer numerically controlled machine comprising: at least firstand second retainers, each of said first and second retainers comprisingone of a spindle retainer, a turret retainer, a first chuck and a secondchuck; at least one cutting tool, said at least one cutting tool beingoperatively connected to said one of said retainers; and a computercontrol system operatively coupled to said first retainer and to saidsecond retainer and causing said first retainer to move relative to saidsecond retainer, said computer control system including a computerreadable medium having disposed thereon code for causing rotation of aworkpiece at a rotational velocity of at least 25 m/min and code forcausing rotation of a tool at a rotational velocity of at least 25m/min, and code for causing said first retainer to move relative to saidsecond retainer to cause said tool to contact said workpiece underprocessing conditions effective to cause discrete chips of material tobe removed from said workpiece.
 46. A method for determining thesuitability of compound machining parameters, comprising: determining,for a workpiece of a preselected size and material, and a tool of apreselected configuration, a relative velocity of rotation between saidtool and said workpiece; and determining whether the power availabilityof a computer numerically controlled machine is sufficient to permitcompound machining at said relative contact rate.
 47. (canceled) 48.(canceled)
 49. (canceled)
 50. A computer program product comprising: acomputer readable medium containing computer program code fordetermining, for a workpiece of a preselected size and material, and atool of a preselected configuration, a relative velocity of rotationbetween said tool and said workpiece; and for determining whether thepower availability of a computer numerically controlled machine issufficient to permit compound machining at said relative contact rate.